tElockv098tE

Hunt Hypothesis

This detection identifies potential file-based threats or specific malware signatures matching the “tElockv098tE” YARA pattern within the Azure Sentinel environment. Proactive hunting for this behavior is essential to uncover early-stage indicators of compromise that may not trigger high-severity alerts, allowing the SOC team to investigate low-fidelity signals before they escalate into significant incidents.

YARA Rule

rule tElockv098tE
{
      meta:
		author="malware-lu"
strings:
		$a0 = { E9 25 E4 FF FF 00 00 00 [8] 00 00 00 00 00 00 00 00 [12] 00 00 00 00 00 00 00 00 [8] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [4] 00 00 00 00 [4] 00 }

condition:
		$a0 at pe.entry_point
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the tElockv098tE detection rule, including recommended filters and exclusions tailored for an enterprise environment:

• Scenario: Microsoft Defender Antivirus Engine Updates

  • Context: The Windows Update service or local Defender engine triggers a background process to download and install definition updates. This often involves the execution of MpCmdRun.exe or MsMpEng.exe, which may match the tElockv098tE signature due to its behavior in scanning system directories.
  • Filter/Exclusion: Create an exclusion for the process path C:\Program Files\Windows Defender\MpCmdRun.exe. Additionally, exclude file paths under C:\ProgramData\Microsoft\Windows Defender\ from the YARA rule scope during standard maintenance windows (e.g., 02:00–04:00 UTC).

• Scenario: Scheduled Veeam Backup Agent Execution

  • Context: During nightly backup cycles, the Veeam Backup & Replication agent (Veeam.Backup.Service.exe) performs heavy I/O operations and scans virtual machine snapshots. The rule may flag the temporary locking mechanisms or the specific binary signature of the backup engine as a potential anomaly.
  • Filter/Exclusion: Add a process exclusion for C:\Program Files\Veeam\Backup and Replication Enterprise Edition\bin64\Veeam.Backup.Service.exe. If the rule relies on file hash matching, whitelist the specific SHA-256 hashes of the installed Veeam version used across the enterprise.

• Scenario: SCCM (MECM) Software Deployment Tasks

  • Context: When System Center Configuration Manager deploys a new application package to endpoints, the ccmexec.exe service executes installation scripts that often involve creating temporary locked files or modifying